The present invention is based on Japanese Patent Application No. 2001-151,202, the contents of which are incorporated by reference.
1. Field of the Invention
The present invention relates to a developing device used in an image forming apparatus such as a copying machine or printer.
2. Description of the Related Art
Developing devices based on the two-component developing method that uses toner and a carrier as the developer and developing devices based on the single-component developing method that does not use a carrier and use only toner are known in the conventional art as developing devices used in image forming apparatuses such as copying machines and printers. As developing devices based on the single-component developing method, those based on the magnetic single-component developing method that includes a magnetic member inside the toner carrier and those based on the non-magnetic single-component developing method that uses a toner carrier that does not include a magnetic member are known.
An example of the developing device using the single-component developing method is shown in FIG. 1. In this developing device, the toner (t) housed in the casing 1 of the system main unit is forwarded by a toner forwarding member 2 to a roller-like toner supply member 3. The toner (t) is supplied to a roller-like toner carrier 4 via the rotation of the toner supply member 3, and the toner carrier 4 further conveys the supplied toner (t) via the rotation thereof. A plate-like regulating member 5 is mounted to the casing 1 at one edge thereof, such that the other edge of the regulating member 5 is in pressure contact with the surface of the toner carrier 4. This regulating member 5 regulates the amount of the toner (t) that is conveyed by the toner carrier 4 and at the same time charges the toner (t). The toner (t) that is regulated and charged in this way is guided by the toner carrier 4 to the developing area in which the toner carrier 4 faces the image carrier 6, whereupon developing takes place.
However, because only a single regulating member 5 is in pressure contact with the surface of the toner carrier 4, problems exist, such as the fact that it is difficult to appropriately regulate the amount of the toner (t) conveyed by the toner carrier 4 and to appropriately charge the toner (t). In particular, the problem exists that it is difficult to reduce the amount of the toner (t) that is conveyed by the toner carrier 4 to the developing area and to charge the toner (t) appropriately.
Systems have been proposed in recent years to address these problems, such as the system that includes two regulating members located inside the casing of the system main unit that are in pressure contact with the surface of the toner carrier, such that the amount of the toner held on the surface of the toner carrier and conveyed is regulated and the toner (t) is charged by the two regulating members, as disclosed by U.S. Pat. No. 6,343,201, and a system in which one edge of a regulating member is mounted to the system main unit and the other edge area of the regulating member is bent such that the regulating member is in contact with the surface of the toner carrier at two or more contact points, and the amount of the toner held on the surface of the toner carrier is regulated and the toner (t) is charged at each contact area, as disclosed by Japanese Laid-Open Patent Application H11-316499.
However, the problems exist that (1) it is troublesome to install two regulating members inside the system main unit such that they are in pressure contact with the surface of the toner carrier in the manner disclosed in U.S. Pat. No. 6,343,201, and (2) construction of such a system is more costly due to the increased number of components. In addition, where the regulating member is attached to the system main unit at one edge thereof while the other edge area thereof is bent such that the regulating member is in contact with the surface of the toner carrier at two or more contact points, as disclosed by Japanese Laid-Open Patent Application H11-316499, the problem exists that one edge of the regulating member must be mounted to the system main unit using mounting members such as screws, which is inconvenient.
An object of the present invention is to provide a developing device capable of regulating the toner amount such that the amount of toner conveyed by the toner carrier to the developing area is reduced, as well as of appropriately charging the toner.
Another object of the present invention is to provide a developing device that comprises a reduced number of components and can accordingly be manufactured more easily and at a lower cost.
Still another object of the present invention is to provide a developing device that does not entail the inconvenient task of mounting the regulating member to the system main unit using mounting members such as screws.
The present invention relates to a developing device for developing images formed on an image carrier comprising: a rotatably mounted roller-like toner carrier for holding a toner on the surface thereof; a plate-like regulating member for regulating an amount of the toner held on the toner carrier, the regulating member having at least one bent part, a first regulating part that is located such that it is in contact with the toner carrier and a second regulating part that is located such that it is in contact with the toner carrier at downstream side of the first regulating part with respect to the surface-moving direction of the toner carrier; and a casing for accommodating the toner, the toner carrier and the regulating member; wherein the regulating member is positioned between the toner carrier and the casing.